Fire smoke dispersion inside and outside of a warehouse building in moderate and strong wind conditions

TL;DR

This study uses CFD simulations to analyze how wind conditions and urban architecture influence smoke dispersion and venting efficiency in a warehouse fire, revealing complex interactions and urban canyon effects.

Contribution

It provides detailed CFD analysis of smoke dispersion in urban environments, highlighting the impact of wind and architecture on smoke control performance and plume behavior.

Findings

Wind significantly affects smoke venting efficiency.

Urban architecture influences smoke dispersion patterns.

Vortices behind tall buildings cause smoke accumulation.

Abstract

A moderate-sized (8 MW) fire was modeled in a warehouse located in an urban area with diverse architecture, under wind conditions. The study investigates the impact of neighboring architecture on the wind field and the resulting effect on smoke control performance and smoke dispersion in the vicinity of the building. 25 CFD simulations were performed using ANSYS Fluent CFD code, for wind velocities of 5 m/s (moderate), 10 m/s (strong) at 12 wind angles each (0 - 330$^\circ$, 30$^\circ$ increment), and at 0 m/s for reference. The results show that the performance of the building smoke venting system was impacted by the wind, reaching 74% - 114% and 78% - 158% of the reference mass flow at moderate and strong wind velocities, respectively. Interestingly, in multiple cases, the exhaust flow rate of the ventilators was increased rather than hindered by the wind. This was attributed to the arrangement of inlets and outlets on the facades and the resulting pressure difference between the wall and roof openings. The smoke plume was highly dependent on the wind angle and the type of architecture upwind and downwind of the fire. Significant urban canyon effects and large vortices forming behind tall buildings were observed, leading to smoke accumulation at a significant distance from the fire.